mips: small changes in VexGuestMIPS{32|64}State structs

mips: small changes in VexGuestMIPS{32|64}State structs

Move host_EvC_FAILADDR and host_EvC_COUNTER fields to the top of the
structure, similar to other architectures.

This fixes

none/tests/libvexmultiarch_test          (stderr)

on some MIPS platforms, as it avoids internal X86/AMD code generator
asserts.

Minor stylish changes included too.

Patch by Aleksandra Karadzic.

git-svn-id: svn://svn.valgrind.org/vex/trunk@3286